US crude prices closed in a bear market on Thursday, extending a rout driven by easing concerns of tight global supplies. Oil prices have tumbled over the past month, with US prices retreating for nine consecutive sessions, amid signs of weaker demand and rising US inventories. The market faced fresh pressure this week after Washington allowed eight countries to continue buying Iranian crude, softening the blow of renewed sanctions.

West Texas Intermediate crude dipped 1.7 percent to $60.67 a barrel Thursday and fell as low as $60.56 a barrel during the session. The sell-off marked a steep decline compared to a four-year high of around $76 seen in early October. A bear market is defined as a 20 percent drop from a recent high. Brent crude was down 1.9 percent at $70.69 a barrel. The international benchmark is down 18.1 percent from its four-year high in October. This is the sixth nine-session losing streak WTI has recorded since 1983, according to Financial Times analysis of Bloomberg data.

WTI most recently fell for nine consecutive sessions in July 2014. It has never closed lower for 10 or more days. Warren Patterson, commodities strategist at ING, said oil prices appeared oversold and he expected an upward correction in the near term, but in 2019 “downward pressure will re-emerge once again.”